The aim of this study is to evaluate bone mass in men with prostate cancer requiring treatment with Gonadotrpin-releasing hormone agonist therapy (GnRH-a). Patients requiring GnRH-a will be compared to age-matched controls with prostate carcinoma not undergoing hormonal ablation. Skeletal integrity will be assessed by state-of-the-art bone density measurement using dual energy xray absorptiometry (DXA) of the forearm, hip, total body, hand and ultrasound of the heel. To assess biochemical parameters of bone turnover, markers of bone resorption (collagen crosslinks) and bone formation (osteocalcin and bone specific alkaline phosphatase) in addition to other assessments of bone metabolism (PTH, 25 hydroxyvitamin D, calcium) will be measured and correlated with skeletal integrity.